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Revision History for A270230

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Showing entries 1-10 | older changes
Decimal expansion of 3/(4*Pi).
(history; published version)
#22 by Charles R Greathouse IV at Sat Oct 01 15:35:13 EDT 2022
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editing

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#21 by Charles R Greathouse IV at Sat Oct 01 15:35:09 EDT 2022
LINKS

<a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>

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approved

editing

#20 by N. J. A. Sloane at Sat Apr 02 23:49:11 EDT 2016
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proposed

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#19 by Michael De Vlieger at Tue Mar 15 14:54:55 EDT 2016
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#18 by Michael De Vlieger at Tue Mar 15 14:54:23 EDT 2016
MATHEMATICA

First@ RealDigits[N[3/4/Pi, 120]] (* Michael De Vlieger, Mar 15 2016 *)

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#17 by Stanislav Sykora at Sun Mar 13 17:29:40 EDT 2016
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#16 by Stanislav Sykora at Sun Mar 13 17:29:36 EDT 2016
COMMENTS

Consider generic prisms with triangular bases (tp) which can be fit inside , enclosed by a sphere, and let f(tp) be the fraction of the sphere volume occupied by any of them (i.e., the ratio of the prism volume to the sphere volume). Then this constant is the supremum of f(tp). It is attained by prisms which have as their base equilateral triangles with edge lengths r*sqrt(2), and rectangular side faces that are r*sqrt(2) wide and r*2/sqrt(3) high, where r is the radius of the enclosing, circumscribed sphere.

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#15 by Stanislav Sykora at Sun Mar 13 17:04:28 EDT 2016
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#14 by Stanislav Sykora at Sun Mar 13 17:04:24 EDT 2016
COMMENTS

Consider generic prisms with triangular bases (tp) which can be fit inside a sphere, and let f(tp) be the fraction of the sphere volume occupied by any of them (i.e., the ratio of the prism volume to the sphere volume). Then this constant is the supremum of f(tp). It is attained by prisms which have as their base equilateral triangles with edge lengths r*sqrt(2), and rectangular side faces that are r*sqrt(2) wide and r*2/sqrt(3) high, where r is the radius of the enclosing , circumscribed sphere.

A Examples of similar constant, but constants obtained for cylinders other shapes enclosed in by spheres, is are: A020760 for cylinders and A165952 for cuboids.

CROSSREFS

Cf. A002193, A019699 (one tenth of 1/a), A020760, A020832 (one tenth of 2/sqrt(3)), A165952.

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editing

#13 by Stanislav Sykora at Sun Mar 13 16:54:34 EDT 2016
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editing

proposed